This invention relates to printing generally and more specifically relates to the production of a transfer medium by a method of transferring a design onto an object by means of printing heat sensitive ink in the desired design onto paper or other printable material by thermal means at a relatively low temperature. The medium so produced may then be used to permanently transfer the design from the medium on to an object by heat applied at a higher temperature, which causes the heat sensitive ink to bond to the object.
Words and designs are frequently printed onto clothing and other textile materials, as well as other objects. Common means of applying such designs to objects include the use of silk screens, and mechanically bonded thermal transfers. Silk screen process is well known in the art, and an example of a mechanical thermal process to textile materials is described in Hare, U.S. Pat. No. 4,224,358.
The use of computer technology has allowed almost instantaneous printing of images. For example, video cameras or scanning may be used to capture an image on magnetic media such as computer hard disks or floppy disks. The image may then be printed by any suitable printing means, including mechanical thermal printers, wet printed (inkjet) heat sensitive transfers and laser printers.
The process of thermal transfers by mechanical means is described in Hare, U.S. Pat. No. 4,773,953. The art, as developed under this patent, is well known and defined in practice. The resulting mechanical image, as transferred, is a surface bonded image with a raised plastic like feel to the surface. The resulting printed image is stiff to the feel, has poor dimensional stability when stretched and poor color range.
Certain ink solids bond to or dye fabrics or other materials as a result of the application of heat. These ink solids liquefy or sublimate upon the application of heat. Sublimation ink solids have been applied from pre-printed media, but the printing of such media with heat sensitive inks has not been done by thermal means at a temperature lower than that which activates the heat sensitive ink.
Sublimation ink solids change to a gas typically in a range of 140.degree. F.-500.degree. F., depending upon the particular ink solid chosen. Once the sublimation occurs, bonding of the ink solid to the application takes place, and the ink is permanently fixed and highly resistant to change or fading caused by laundry products.